Abstract
In order to rationalize structural maintenance, a non-contact vibration measurement system with Laser Doppler Vibrometer (LDV) has been constructed in laboratory testing. However, in the case of measuring vibration of existing real structures, the objectives would possess low laser reflection characteristics. Therefore, it is difficult to apply an LDV to these. In this study, the measurement system is improved with an automatic searching function of the optical point that could give the maximum laser reflection around the objective points. This improvement produces a tremendous advance in measurement accuracy for real structures. As a case study, vibration measurement is conducted at a steel girder and a reinforced concrete of existing viaduct. The mode shapes are identified and quality of measurement is also evaluated quantitatively.
